1. Technical Field
The present invention relates to network systems and more particularly to a network where a wireless interface is extended through a dedicated optical fiber link.
2. Description of the Related Art
The emergence of broadband applications like internet protocol (IP) television (IPTV) stimulates the quick deployment of “fiber to the ‘x’” (FTTx, fiber to a particular type of customer premises), especially with Passive Optical Networks (PON), due to its low cost and high capacity. With the growing amount of PON subscribers, annual sales of the PON equipment are projected to grow accordingly.
Broadband wireless access (BWA) technology has been drawing increased interest due to its high flexibility and possibility for quick service deployment, which enables broadband services to traditional wireline users and to users in rural areas, where cable and DSL are not available. After the standardization of IEEE 802.16d/e WiMAX (Worldwide Interoperability for Microwave Access), the speed of adopting BWA increased greatly. Therefore, the global WiMAX equipment market is predicted to grow substantially.
Within existing access network solutions, service providers have treated wireless and wireline networks separately. This includes setting up dedicated links to connect these separate networks.
For dedicated links, to connect base stations from a central office, the current solutions use a plurality of time division multiplexed (TDM) links like T1/E1 or T3/OC-3, asynchronous packet links like Ethernet, or microwave/wireless point-to-point links, and terminate the subscriber station traffic at the base station. In other solutions, a radio frequency over fiber (RoF) is employed to transmit information. Such solutions require dedicated fiber links for each base station; thus requiring costly implementation.
These solutions have the following drawbacks. They require dedicated wireline connections to the central office. Note although the microwave/wireless point-to-point links eliminate the dedicated wireline connection) additional microwave/wireless equipment is needed, which is expensive to purchase and maintain. In addition, the interfaces and/or equipment between the base stations and the central office increase management costs.
Another approach takes advantage of the existing network infrastructure. For example, to provide wireless services to residential areas, a pre-constructed PON network can be employed, in which the wireless traffic is terminated at the PON ONUs (Optical Network Unit). This approach is similar to those described above except that the wireline capacity is not dedicated to the base stations, and it is shared among different applications. This solution needs to allocate certain wireline bandwidth to carry wireless services; thus, it is often difficult to realize in heavy-traffic scenarios.